1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, NameBindingKind, ParentScope, PathResult};
12 use crate::{ResolutionError, Resolver, Segment, UseError};
14 use rustc::{bug, lint, span_bug};
15 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
16 use rustc_errors::DiagnosticId;
17 use rustc_hir::def::Namespace::{self, *};
18 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
19 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
20 use rustc_hir::TraitCandidate;
21 use rustc_span::symbol::{kw, sym};
23 use smallvec::{smallvec, SmallVec};
26 use syntax::util::lev_distance::find_best_match_for_name;
27 use syntax::visit::{self, FnKind, Visitor};
28 use syntax::{unwrap_or, walk_list};
31 use std::collections::BTreeSet;
32 use std::mem::replace;
36 type Res = def::Res<NodeId>;
38 type IdentMap<T> = FxHashMap<Ident, T>;
40 /// Map from the name in a pattern to its binding mode.
41 type BindingMap = IdentMap<BindingInfo>;
43 #[derive(Copy, Clone, Debug)]
46 binding_mode: BindingMode,
49 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
58 fn descr(self) -> &'static str {
60 PatternSource::Match => "match binding",
61 PatternSource::Let => "let binding",
62 PatternSource::For => "for binding",
63 PatternSource::FnParam => "function parameter",
68 /// Denotes whether the context for the set of already bound bindings is a `Product`
69 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
70 /// See those functions for more information.
73 /// A product pattern context, e.g., `Variant(a, b)`.
75 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
79 /// Does this the item (from the item rib scope) allow generic parameters?
80 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
81 crate enum HasGenericParams {
86 /// The rib kind restricts certain accesses,
87 /// e.g. to a `Res::Local` of an outer item.
88 #[derive(Copy, Clone, Debug)]
89 crate enum RibKind<'a> {
90 /// No restriction needs to be applied.
93 /// We passed through an impl or trait and are now in one of its
94 /// methods or associated types. Allow references to ty params that impl or trait
95 /// binds. Disallow any other upvars (including other ty params that are
99 /// We passed through a function definition. Disallow upvars.
100 /// Permit only those const parameters that are specified in the function's generics.
103 /// We passed through an item scope. Disallow upvars.
104 ItemRibKind(HasGenericParams),
106 /// We're in a constant item. Can't refer to dynamic stuff.
109 /// We passed through a module.
110 ModuleRibKind(Module<'a>),
112 /// We passed through a `macro_rules!` statement
113 MacroDefinition(DefId),
115 /// All bindings in this rib are type parameters that can't be used
116 /// from the default of a type parameter because they're not declared
117 /// before said type parameter. Also see the `visit_generics` override.
118 ForwardTyParamBanRibKind,
122 // Whether this rib kind contains generic parameters, as opposed to local
124 crate fn contains_params(&self) -> bool {
126 NormalRibKind | FnItemRibKind | ConstantItemRibKind | ModuleRibKind(_)
127 | MacroDefinition(_) => false,
128 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
133 /// A single local scope.
135 /// A rib represents a scope names can live in. Note that these appear in many places, not just
136 /// around braces. At any place where the list of accessible names (of the given namespace)
137 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
138 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
141 /// Different [rib kinds](enum.RibKind) are transparent for different names.
143 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
144 /// resolving, the name is looked up from inside out.
146 crate struct Rib<'a, R = Res> {
147 pub bindings: IdentMap<R>,
148 pub kind: RibKind<'a>,
151 impl<'a, R> Rib<'a, R> {
152 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
153 Rib { bindings: Default::default(), kind }
157 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
158 crate enum AliasPossibility {
163 #[derive(Copy, Clone, Debug)]
164 crate enum PathSource<'a> {
165 // Type paths `Path`.
167 // Trait paths in bounds or impls.
168 Trait(AliasPossibility),
169 // Expression paths `path`, with optional parent context.
170 Expr(Option<&'a Expr>),
171 // Paths in path patterns `Path`.
173 // Paths in struct expressions and patterns `Path { .. }`.
175 // Paths in tuple struct patterns `Path(..)`.
177 // `m::A::B` in `<T as m::A>::B::C`.
178 TraitItem(Namespace),
181 impl<'a> PathSource<'a> {
182 fn namespace(self) -> Namespace {
184 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
185 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
186 PathSource::TraitItem(ns) => ns,
190 fn defer_to_typeck(self) -> bool {
193 | PathSource::Expr(..)
196 | PathSource::TupleStruct => true,
197 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
201 fn descr_expected(self) -> &'static str {
203 PathSource::Type => "type",
204 PathSource::Trait(_) => "trait",
205 PathSource::Pat => "unit struct, unit variant or constant",
206 PathSource::Struct => "struct, variant or union type",
207 PathSource::TupleStruct => "tuple struct or tuple variant",
208 PathSource::TraitItem(ns) => match ns {
209 TypeNS => "associated type",
210 ValueNS => "method or associated constant",
211 MacroNS => bug!("associated macro"),
213 PathSource::Expr(parent) => match &parent.as_ref().map(|p| &p.kind) {
214 // "function" here means "anything callable" rather than `DefKind::Fn`,
215 // this is not precise but usually more helpful than just "value".
216 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
217 ExprKind::Path(_, path) => {
218 let mut msg = "function";
219 if let Some(segment) = path.segments.iter().last() {
220 if let Some(c) = segment.ident.to_string().chars().next() {
221 if c.is_uppercase() {
222 msg = "function, tuple struct or tuple variant";
235 crate fn is_expected(self, res: Res) -> bool {
237 PathSource::Type => match res {
238 Res::Def(DefKind::Struct, _)
239 | Res::Def(DefKind::Union, _)
240 | Res::Def(DefKind::Enum, _)
241 | Res::Def(DefKind::Trait, _)
242 | Res::Def(DefKind::TraitAlias, _)
243 | Res::Def(DefKind::TyAlias, _)
244 | Res::Def(DefKind::AssocTy, _)
246 | Res::Def(DefKind::TyParam, _)
248 | Res::Def(DefKind::OpaqueTy, _)
249 | Res::Def(DefKind::ForeignTy, _) => true,
252 PathSource::Trait(AliasPossibility::No) => match res {
253 Res::Def(DefKind::Trait, _) => true,
256 PathSource::Trait(AliasPossibility::Maybe) => match res {
257 Res::Def(DefKind::Trait, _) => true,
258 Res::Def(DefKind::TraitAlias, _) => true,
261 PathSource::Expr(..) => match res {
262 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
263 | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
264 | Res::Def(DefKind::Const, _)
265 | Res::Def(DefKind::Static, _)
267 | Res::Def(DefKind::Fn, _)
268 | Res::Def(DefKind::Method, _)
269 | Res::Def(DefKind::AssocConst, _)
271 | Res::Def(DefKind::ConstParam, _) => true,
274 PathSource::Pat => match res {
275 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
276 | Res::Def(DefKind::Const, _)
277 | Res::Def(DefKind::AssocConst, _)
278 | Res::SelfCtor(..) => true,
281 PathSource::TupleStruct => match res {
282 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
285 PathSource::Struct => match res {
286 Res::Def(DefKind::Struct, _)
287 | Res::Def(DefKind::Union, _)
288 | Res::Def(DefKind::Variant, _)
289 | Res::Def(DefKind::TyAlias, _)
290 | Res::Def(DefKind::AssocTy, _)
291 | Res::SelfTy(..) => true,
294 PathSource::TraitItem(ns) => match res {
295 Res::Def(DefKind::AssocConst, _) | Res::Def(DefKind::Method, _)
300 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
306 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
307 use rustc_errors::error_code;
308 match (self, has_unexpected_resolution) {
309 (PathSource::Trait(_), true) => error_code!(E0404),
310 (PathSource::Trait(_), false) => error_code!(E0405),
311 (PathSource::Type, true) => error_code!(E0573),
312 (PathSource::Type, false) => error_code!(E0412),
313 (PathSource::Struct, true) => error_code!(E0574),
314 (PathSource::Struct, false) => error_code!(E0422),
315 (PathSource::Expr(..), true) => error_code!(E0423),
316 (PathSource::Expr(..), false) => error_code!(E0425),
317 (PathSource::Pat, true) | (PathSource::TupleStruct, true) => error_code!(E0532),
318 (PathSource::Pat, false) | (PathSource::TupleStruct, false) => error_code!(E0531),
319 (PathSource::TraitItem(..), true) => error_code!(E0575),
320 (PathSource::TraitItem(..), false) => error_code!(E0576),
326 struct DiagnosticMetadata {
327 /// The current trait's associated types' ident, used for diagnostic suggestions.
328 current_trait_assoc_types: Vec<Ident>,
330 /// The current self type if inside an impl (used for better errors).
331 current_self_type: Option<Ty>,
333 /// The current self item if inside an ADT (used for better errors).
334 current_self_item: Option<NodeId>,
336 /// The current enclosing function (used for better errors).
337 current_function: Option<Span>,
339 /// A list of labels as of yet unused. Labels will be removed from this map when
340 /// they are used (in a `break` or `continue` statement)
341 unused_labels: FxHashMap<NodeId, Span>,
343 /// Only used for better errors on `fn(): fn()`.
344 current_type_ascription: Vec<Span>,
346 /// Only used for better errors on `let <pat>: <expr, not type>;`.
347 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
350 struct LateResolutionVisitor<'a, 'b> {
351 r: &'b mut Resolver<'a>,
353 /// The module that represents the current item scope.
354 parent_scope: ParentScope<'a>,
356 /// The current set of local scopes for types and values.
357 /// FIXME #4948: Reuse ribs to avoid allocation.
358 ribs: PerNS<Vec<Rib<'a>>>,
360 /// The current set of local scopes, for labels.
361 label_ribs: Vec<Rib<'a, NodeId>>,
363 /// The trait that the current context can refer to.
364 current_trait_ref: Option<(Module<'a>, TraitRef)>,
366 /// Fields used to add information to diagnostic errors.
367 diagnostic_metadata: DiagnosticMetadata,
370 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
371 impl<'a, 'tcx> Visitor<'tcx> for LateResolutionVisitor<'a, '_> {
372 fn visit_item(&mut self, item: &'tcx Item) {
373 self.resolve_item(item);
375 fn visit_arm(&mut self, arm: &'tcx Arm) {
376 self.resolve_arm(arm);
378 fn visit_block(&mut self, block: &'tcx Block) {
379 self.resolve_block(block);
381 fn visit_anon_const(&mut self, constant: &'tcx AnonConst) {
382 debug!("visit_anon_const {:?}", constant);
383 self.with_constant_rib(|this| {
384 visit::walk_anon_const(this, constant);
387 fn visit_expr(&mut self, expr: &'tcx Expr) {
388 self.resolve_expr(expr, None);
390 fn visit_local(&mut self, local: &'tcx Local) {
391 let local_spans = match local.pat.kind {
392 // We check for this to avoid tuple struct fields.
393 PatKind::Wild => None,
396 local.ty.as_ref().map(|ty| ty.span),
397 local.init.as_ref().map(|init| init.span),
400 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
401 self.resolve_local(local);
402 self.diagnostic_metadata.current_let_binding = original;
404 fn visit_ty(&mut self, ty: &'tcx Ty) {
406 TyKind::Path(ref qself, ref path) => {
407 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
409 TyKind::ImplicitSelf => {
410 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
412 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
413 .map_or(Res::Err, |d| d.res());
414 self.r.record_partial_res(ty.id, PartialRes::new(res));
418 visit::walk_ty(self, ty);
420 fn visit_poly_trait_ref(&mut self, tref: &'tcx PolyTraitRef, m: &'tcx TraitBoundModifier) {
421 self.smart_resolve_path(
422 tref.trait_ref.ref_id,
424 &tref.trait_ref.path,
425 PathSource::Trait(AliasPossibility::Maybe),
427 visit::walk_poly_trait_ref(self, tref, m);
429 fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
430 match foreign_item.kind {
431 ForeignItemKind::Fn(_, ref generics) => {
432 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
433 visit::walk_foreign_item(this, foreign_item);
436 ForeignItemKind::Static(..) => {
437 self.with_item_rib(HasGenericParams::No, |this| {
438 visit::walk_foreign_item(this, foreign_item);
441 ForeignItemKind::Ty | ForeignItemKind::Macro(..) => {
442 visit::walk_foreign_item(self, foreign_item);
446 fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, declaration: &'tcx FnDecl, sp: Span, _: NodeId) {
447 let previous_value = replace(&mut self.diagnostic_metadata.current_function, Some(sp));
448 debug!("(resolving function) entering function");
449 let rib_kind = match fn_kind {
450 FnKind::ItemFn(..) => FnItemRibKind,
451 FnKind::Method(..) | FnKind::Closure(_) => NormalRibKind,
454 // Create a value rib for the function.
455 self.with_rib(ValueNS, rib_kind, |this| {
456 // Create a label rib for the function.
457 this.with_label_rib(rib_kind, |this| {
458 // Add each argument to the rib.
459 this.resolve_params(&declaration.inputs);
461 visit::walk_fn_ret_ty(this, &declaration.output);
463 // Resolve the function body, potentially inside the body of an async closure
465 FnKind::ItemFn(.., body) | FnKind::Method(.., body) => this.visit_block(body),
466 FnKind::Closure(body) => this.visit_expr(body),
469 debug!("(resolving function) leaving function");
472 self.diagnostic_metadata.current_function = previous_value;
475 fn visit_generics(&mut self, generics: &'tcx Generics) {
476 // For type parameter defaults, we have to ban access
477 // to following type parameters, as the InternalSubsts can only
478 // provide previous type parameters as they're built. We
479 // put all the parameters on the ban list and then remove
480 // them one by one as they are processed and become available.
481 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
482 let mut found_default = false;
483 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
484 |param| match param.kind {
485 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
486 GenericParamKind::Type { ref default, .. } => {
487 found_default |= default.is_some();
488 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
493 // rust-lang/rust#61631: The type `Self` is essentially
494 // another type parameter. For ADTs, we consider it
495 // well-defined only after all of the ADT type parameters have
496 // been provided. Therefore, we do not allow use of `Self`
497 // anywhere in ADT type parameter defaults.
499 // (We however cannot ban `Self` for defaults on *all* generic
500 // lists; e.g. trait generics can usefully refer to `Self`,
501 // such as in the case of `trait Add<Rhs = Self>`.)
502 if self.diagnostic_metadata.current_self_item.is_some() {
503 // (`Some` if + only if we are in ADT's generics.)
504 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
507 for param in &generics.params {
509 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
510 GenericParamKind::Type { ref default, .. } => {
511 for bound in ¶m.bounds {
512 self.visit_param_bound(bound);
515 if let Some(ref ty) = default {
516 self.ribs[TypeNS].push(default_ban_rib);
518 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
521 // Allow all following defaults to refer to this type parameter.
522 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
524 GenericParamKind::Const { ref ty } => {
525 for bound in ¶m.bounds {
526 self.visit_param_bound(bound);
532 for p in &generics.where_clause.predicates {
533 self.visit_where_predicate(p);
537 fn visit_generic_arg(&mut self, arg: &'tcx GenericArg) {
538 debug!("visit_generic_arg({:?})", arg);
540 GenericArg::Type(ref ty) => {
541 // We parse const arguments as path types as we cannot distiguish them durring
542 // parsing. We try to resolve that ambiguity by attempting resolution the type
543 // namespace first, and if that fails we try again in the value namespace. If
544 // resolution in the value namespace succeeds, we have an generic const argument on
546 if let TyKind::Path(ref qself, ref path) = ty.kind {
547 // We cannot disambiguate multi-segment paths right now as that requires type
549 if path.segments.len() == 1 && path.segments[0].args.is_none() {
550 let mut check_ns = |ns| {
551 self.resolve_ident_in_lexical_scope(
552 path.segments[0].ident,
560 if !check_ns(TypeNS) && check_ns(ValueNS) {
561 // This must be equivalent to `visit_anon_const`, but we cannot call it
562 // directly due to visitor lifetimes so we have to copy-paste some code.
563 self.with_constant_rib(|this| {
564 this.smart_resolve_path(
568 PathSource::Expr(None),
571 if let Some(ref qself) = *qself {
572 this.visit_ty(&qself.ty);
574 this.visit_path(path, ty.id);
584 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
585 GenericArg::Const(ct) => self.visit_anon_const(ct),
590 impl<'a, 'b> LateResolutionVisitor<'a, '_> {
591 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b> {
592 // During late resolution we only track the module component of the parent scope,
593 // although it may be useful to track other components as well for diagnostics.
594 let graph_root = resolver.graph_root;
595 let parent_scope = ParentScope::module(graph_root);
596 let start_rib_kind = ModuleRibKind(graph_root);
597 LateResolutionVisitor {
601 value_ns: vec![Rib::new(start_rib_kind)],
602 type_ns: vec![Rib::new(start_rib_kind)],
603 macro_ns: vec![Rib::new(start_rib_kind)],
605 label_ribs: Vec::new(),
606 current_trait_ref: None,
607 diagnostic_metadata: DiagnosticMetadata::default(),
611 fn resolve_ident_in_lexical_scope(
615 record_used_id: Option<NodeId>,
617 ) -> Option<LexicalScopeBinding<'a>> {
618 self.r.resolve_ident_in_lexical_scope(
631 opt_ns: Option<Namespace>, // `None` indicates a module path in import
634 crate_lint: CrateLint,
635 ) -> PathResult<'a> {
636 self.r.resolve_path_with_ribs(
649 // We maintain a list of value ribs and type ribs.
651 // Simultaneously, we keep track of the current position in the module
652 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
653 // the value or type namespaces, we first look through all the ribs and
654 // then query the module graph. When we resolve a name in the module
655 // namespace, we can skip all the ribs (since nested modules are not
656 // allowed within blocks in Rust) and jump straight to the current module
659 // Named implementations are handled separately. When we find a method
660 // call, we consult the module node to find all of the implementations in
661 // scope. This information is lazily cached in the module node. We then
662 // generate a fake "implementation scope" containing all the
663 // implementations thus found, for compatibility with old resolve pass.
665 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
670 work: impl FnOnce(&mut Self) -> T,
672 self.ribs[ns].push(Rib::new(kind));
673 let ret = work(self);
678 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
679 let id = self.r.definitions.local_def_id(id);
680 let module = self.r.module_map.get(&id).cloned(); // clones a reference
681 if let Some(module) = module {
682 // Move down in the graph.
683 let orig_module = replace(&mut self.parent_scope.module, module);
684 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
685 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
687 this.parent_scope.module = orig_module;
696 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
697 /// is returned by the given predicate function
699 /// Stops after meeting a closure.
700 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
702 P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>,
704 for rib in self.label_ribs.iter().rev() {
707 // If an invocation of this macro created `ident`, give up on `ident`
708 // and switch to `ident`'s source from the macro definition.
709 MacroDefinition(def) => {
710 if def == self.r.macro_def(ident.span.ctxt()) {
711 ident.span.remove_mark();
715 // Do not resolve labels across function boundary
719 let r = pred(rib, ident);
727 fn resolve_adt(&mut self, item: &Item, generics: &Generics) {
728 debug!("resolve_adt");
729 self.with_current_self_item(item, |this| {
730 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
731 let item_def_id = this.r.definitions.local_def_id(item.id);
732 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
733 visit::walk_item(this, item);
739 fn future_proof_import(&mut self, use_tree: &UseTree) {
740 let segments = &use_tree.prefix.segments;
741 if !segments.is_empty() {
742 let ident = segments[0].ident;
743 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
747 let nss = match use_tree.kind {
748 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
751 let report_error = |this: &Self, ns| {
752 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
753 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
757 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
758 Some(LexicalScopeBinding::Res(..)) => {
759 report_error(self, ns);
761 Some(LexicalScopeBinding::Item(binding)) => {
762 let orig_blacklisted_binding =
763 replace(&mut self.r.blacklisted_binding, Some(binding));
764 if let Some(LexicalScopeBinding::Res(..)) = self
765 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
767 report_error(self, ns);
769 self.r.blacklisted_binding = orig_blacklisted_binding;
774 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
775 for (use_tree, _) in use_trees {
776 self.future_proof_import(use_tree);
781 fn resolve_item(&mut self, item: &Item) {
782 let name = item.ident.name;
783 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
786 ItemKind::TyAlias(_, ref generics) | ItemKind::Fn(_, ref generics, _) => {
787 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
788 visit::walk_item(this, item)
792 ItemKind::Enum(_, ref generics)
793 | ItemKind::Struct(_, ref generics)
794 | ItemKind::Union(_, ref generics) => {
795 self.resolve_adt(item, generics);
802 items: ref impl_items,
805 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
808 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
809 // Create a new rib for the trait-wide type parameters.
810 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
811 let local_def_id = this.r.definitions.local_def_id(item.id);
812 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
813 this.visit_generics(generics);
814 walk_list!(this, visit_param_bound, bounds);
816 for trait_item in trait_items {
817 this.with_trait_items(trait_items, |this| {
818 this.with_generic_param_rib(
819 &trait_item.generics,
822 match trait_item.kind {
823 AssocItemKind::Const(ref ty, ref default) => {
826 // Only impose the restrictions of
827 // ConstRibKind for an actual constant
828 // expression in a provided default.
829 if let Some(ref expr) = *default {
830 this.with_constant_rib(|this| {
831 this.visit_expr(expr);
835 AssocItemKind::Fn(_, _) => {
836 visit::walk_trait_item(this, trait_item)
838 AssocItemKind::TyAlias(..) => {
839 visit::walk_trait_item(this, trait_item)
841 AssocItemKind::Macro(_) => {
842 panic!("unexpanded macro in resolve!")
853 ItemKind::TraitAlias(ref generics, ref bounds) => {
854 // Create a new rib for the trait-wide type parameters.
855 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
856 let local_def_id = this.r.definitions.local_def_id(item.id);
857 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
858 this.visit_generics(generics);
859 walk_list!(this, visit_param_bound, bounds);
864 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
865 self.with_scope(item.id, |this| {
866 visit::walk_item(this, item);
870 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(ref ty, ref expr) => {
871 debug!("resolve_item ItemKind::Const");
872 self.with_item_rib(HasGenericParams::No, |this| {
874 this.with_constant_rib(|this| {
875 this.visit_expr(expr);
880 ItemKind::Use(ref use_tree) => {
881 self.future_proof_import(use_tree);
884 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
885 // do nothing, these are just around to be encoded
888 ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
892 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
894 F: FnOnce(&mut Self),
896 debug!("with_generic_param_rib");
897 let mut function_type_rib = Rib::new(kind);
898 let mut function_value_rib = Rib::new(kind);
899 let mut seen_bindings = FxHashMap::default();
901 // We also can't shadow bindings from the parent item
902 if let AssocItemRibKind = kind {
903 let mut add_bindings_for_ns = |ns| {
904 let parent_rib = self.ribs[ns]
906 .rfind(|r| if let ItemRibKind(_) = r.kind { true } else { false })
907 .expect("associated item outside of an item");
909 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
911 add_bindings_for_ns(ValueNS);
912 add_bindings_for_ns(TypeNS);
915 for param in &generics.params {
916 if let GenericParamKind::Lifetime { .. } = param.kind {
920 let def_kind = match param.kind {
921 GenericParamKind::Type { .. } => DefKind::TyParam,
922 GenericParamKind::Const { .. } => DefKind::ConstParam,
926 let ident = param.ident.modern();
927 debug!("with_generic_param_rib: {}", param.id);
929 if seen_bindings.contains_key(&ident) {
930 let span = seen_bindings.get(&ident).unwrap();
931 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, *span);
932 self.r.report_error(param.ident.span, err);
934 seen_bindings.entry(ident).or_insert(param.ident.span);
936 // Plain insert (no renaming).
937 let res = Res::Def(def_kind, self.r.definitions.local_def_id(param.id));
940 GenericParamKind::Type { .. } => {
941 function_type_rib.bindings.insert(ident, res);
942 self.r.record_partial_res(param.id, PartialRes::new(res));
944 GenericParamKind::Const { .. } => {
945 function_value_rib.bindings.insert(ident, res);
946 self.r.record_partial_res(param.id, PartialRes::new(res));
952 self.ribs[ValueNS].push(function_value_rib);
953 self.ribs[TypeNS].push(function_type_rib);
957 self.ribs[TypeNS].pop();
958 self.ribs[ValueNS].pop();
961 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
962 self.label_ribs.push(Rib::new(kind));
964 self.label_ribs.pop();
967 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
968 let kind = ItemRibKind(has_generic_params);
969 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
972 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
973 debug!("with_constant_rib");
974 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
975 this.with_label_rib(ConstantItemRibKind, f);
979 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
980 // Handle nested impls (inside fn bodies)
982 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
983 let result = f(self);
984 self.diagnostic_metadata.current_self_type = previous_value;
988 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
990 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
991 let result = f(self);
992 self.diagnostic_metadata.current_self_item = previous_value;
996 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
997 fn with_trait_items<T>(
999 trait_items: &Vec<AssocItem>,
1000 f: impl FnOnce(&mut Self) -> T,
1002 let trait_assoc_types = replace(
1003 &mut self.diagnostic_metadata.current_trait_assoc_types,
1006 .filter_map(|item| match &item.kind {
1007 AssocItemKind::TyAlias(bounds, _) if bounds.len() == 0 => Some(item.ident),
1012 let result = f(self);
1013 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
1017 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1018 fn with_optional_trait_ref<T>(
1020 opt_trait_ref: Option<&TraitRef>,
1021 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1023 let mut new_val = None;
1024 let mut new_id = None;
1025 if let Some(trait_ref) = opt_trait_ref {
1026 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1028 .smart_resolve_path_fragment(
1032 trait_ref.path.span,
1033 PathSource::Trait(AliasPossibility::No),
1034 CrateLint::SimplePath(trait_ref.ref_id),
1037 if res != Res::Err {
1038 new_id = Some(res.def_id());
1039 let span = trait_ref.path.span;
1040 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1045 CrateLint::SimplePath(trait_ref.ref_id),
1047 new_val = Some((module, trait_ref.clone()));
1051 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1052 let result = f(self, new_id);
1053 self.current_trait_ref = original_trait_ref;
1057 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1058 let mut self_type_rib = Rib::new(NormalRibKind);
1060 // Plain insert (no renaming, since types are not currently hygienic)
1061 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1062 self.ribs[ns].push(self_type_rib);
1064 self.ribs[ns].pop();
1067 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1068 self.with_self_rib_ns(TypeNS, self_res, f)
1071 fn resolve_implementation(
1073 generics: &Generics,
1074 opt_trait_reference: &Option<TraitRef>,
1077 impl_items: &[AssocItem],
1079 debug!("resolve_implementation");
1080 // If applicable, create a rib for the type parameters.
1081 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1082 // Dummy self type for better errors if `Self` is used in the trait path.
1083 this.with_self_rib(Res::SelfTy(None, None), |this| {
1084 // Resolve the trait reference, if necessary.
1085 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1086 let item_def_id = this.r.definitions.local_def_id(item_id);
1087 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1088 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1089 // Resolve type arguments in the trait path.
1090 visit::walk_trait_ref(this, trait_ref);
1092 // Resolve the self type.
1093 this.visit_ty(self_type);
1094 // Resolve the generic parameters.
1095 this.visit_generics(generics);
1096 // Resolve the items within the impl.
1097 this.with_current_self_type(self_type, |this| {
1098 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1099 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1100 for impl_item in impl_items {
1101 // We also need a new scope for the impl item type parameters.
1102 this.with_generic_param_rib(&impl_item.generics,
1105 use crate::ResolutionError::*;
1106 match impl_item.kind {
1107 AssocItemKind::Const(..) => {
1109 "resolve_implementation AssocItemKind::Const",
1111 // If this is a trait impl, ensure the const
1113 this.check_trait_item(
1117 |n, s| ConstNotMemberOfTrait(n, s),
1120 this.with_constant_rib(|this| {
1121 visit::walk_impl_item(this, impl_item)
1124 AssocItemKind::Fn(..) => {
1125 // If this is a trait impl, ensure the method
1127 this.check_trait_item(impl_item.ident,
1130 |n, s| MethodNotMemberOfTrait(n, s));
1132 visit::walk_impl_item(this, impl_item);
1134 AssocItemKind::TyAlias(_, _) => {
1135 // If this is a trait impl, ensure the type
1137 this.check_trait_item(impl_item.ident,
1140 |n, s| TypeNotMemberOfTrait(n, s));
1142 visit::walk_impl_item(this, impl_item);
1144 AssocItemKind::Macro(_) =>
1145 panic!("unexpanded macro in resolve!"),
1157 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1159 F: FnOnce(Name, &str) -> ResolutionError<'_>,
1161 // If there is a TraitRef in scope for an impl, then the method must be in the
1163 if let Some((module, _)) = self.current_trait_ref {
1166 .resolve_ident_in_module(
1167 ModuleOrUniformRoot::Module(module),
1176 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1177 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1182 fn resolve_params(&mut self, params: &[Param]) {
1183 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1184 for Param { pat, ty, .. } in params {
1185 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1187 debug!("(resolving function / closure) recorded parameter");
1191 fn resolve_local(&mut self, local: &Local) {
1192 // Resolve the type.
1193 walk_list!(self, visit_ty, &local.ty);
1195 // Resolve the initializer.
1196 walk_list!(self, visit_expr, &local.init);
1198 // Resolve the pattern.
1199 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1202 /// build a map from pattern identifiers to binding-info's.
1203 /// this is done hygienically. This could arise for a macro
1204 /// that expands into an or-pattern where one 'x' was from the
1205 /// user and one 'x' came from the macro.
1206 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1207 let mut binding_map = FxHashMap::default();
1209 pat.walk(&mut |pat| {
1211 PatKind::Ident(binding_mode, ident, ref sub_pat)
1212 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1214 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1216 PatKind::Or(ref ps) => {
1217 // Check the consistency of this or-pattern and
1218 // then add all bindings to the larger map.
1219 for bm in self.check_consistent_bindings(ps) {
1220 binding_map.extend(bm);
1233 fn is_base_res_local(&self, nid: NodeId) -> bool {
1234 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1235 Some(Res::Local(..)) => true,
1240 /// Checks that all of the arms in an or-pattern have exactly the
1241 /// same set of bindings, with the same binding modes for each.
1242 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1243 let mut missing_vars = FxHashMap::default();
1244 let mut inconsistent_vars = FxHashMap::default();
1246 // 1) Compute the binding maps of all arms.
1247 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1249 // 2) Record any missing bindings or binding mode inconsistencies.
1250 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1251 // Check against all arms except for the same pattern which is always self-consistent.
1255 .filter(|(_, pat)| pat.id != pat_outer.id)
1256 .flat_map(|(idx, _)| maps[idx].iter())
1257 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1259 for (name, info, &binding_inner) in inners {
1262 // The inner binding is missing in the outer.
1264 missing_vars.entry(name).or_insert_with(|| BindingError {
1266 origin: BTreeSet::new(),
1267 target: BTreeSet::new(),
1268 could_be_path: name.as_str().starts_with(char::is_uppercase),
1270 binding_error.origin.insert(binding_inner.span);
1271 binding_error.target.insert(pat_outer.span);
1273 Some(binding_outer) => {
1274 if binding_outer.binding_mode != binding_inner.binding_mode {
1275 // The binding modes in the outer and inner bindings differ.
1278 .or_insert((binding_inner.span, binding_outer.span));
1285 // 3) Report all missing variables we found.
1286 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1287 missing_vars.sort();
1288 for (name, mut v) in missing_vars {
1289 if inconsistent_vars.contains_key(name) {
1290 v.could_be_path = false;
1292 self.r.report_error(
1293 *v.origin.iter().next().unwrap(),
1294 ResolutionError::VariableNotBoundInPattern(v),
1298 // 4) Report all inconsistencies in binding modes we found.
1299 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1300 inconsistent_vars.sort();
1301 for (name, v) in inconsistent_vars {
1302 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1305 // 5) Finally bubble up all the binding maps.
1309 /// Check the consistency of the outermost or-patterns.
1310 fn check_consistent_bindings_top(&mut self, pat: &Pat) {
1311 pat.walk(&mut |pat| match pat.kind {
1312 PatKind::Or(ref ps) => {
1313 self.check_consistent_bindings(ps);
1320 fn resolve_arm(&mut self, arm: &Arm) {
1321 self.with_rib(ValueNS, NormalRibKind, |this| {
1322 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1323 walk_list!(this, visit_expr, &arm.guard);
1324 this.visit_expr(&arm.body);
1328 /// Arising from `source`, resolve a top level pattern.
1329 fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) {
1330 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1331 self.resolve_pattern(pat, pat_src, &mut bindings);
1337 pat_src: PatternSource,
1338 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1340 self.resolve_pattern_inner(pat, pat_src, bindings);
1341 // This has to happen *after* we determine which pat_idents are variants:
1342 self.check_consistent_bindings_top(pat);
1343 visit::walk_pat(self, pat);
1346 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1350 /// A stack of sets of bindings accumulated.
1352 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1353 /// be interpreted as re-binding an already bound binding. This results in an error.
1354 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1355 /// in reusing this binding rather than creating a fresh one.
1357 /// When called at the top level, the stack must have a single element
1358 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1359 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1360 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1361 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1362 /// When a whole or-pattern has been dealt with, the thing happens.
1364 /// See the implementation and `fresh_binding` for more details.
1365 fn resolve_pattern_inner(
1368 pat_src: PatternSource,
1369 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1371 // Visit all direct subpatterns of this pattern.
1372 pat.walk(&mut |pat| {
1373 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1375 PatKind::Ident(bmode, ident, ref sub) => {
1376 // First try to resolve the identifier as some existing entity,
1377 // then fall back to a fresh binding.
1378 let has_sub = sub.is_some();
1380 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1381 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1382 self.r.record_partial_res(pat.id, PartialRes::new(res));
1384 PatKind::TupleStruct(ref path, ..) => {
1385 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1387 PatKind::Path(ref qself, ref path) => {
1388 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1390 PatKind::Struct(ref path, ..) => {
1391 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1393 PatKind::Or(ref ps) => {
1394 // Add a new set of bindings to the stack. `Or` here records that when a
1395 // binding already exists in this set, it should not result in an error because
1396 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1397 bindings.push((PatBoundCtx::Or, Default::default()));
1399 // Now we need to switch back to a product context so that each
1400 // part of the or-pattern internally rejects already bound names.
1401 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1402 bindings.push((PatBoundCtx::Product, Default::default()));
1403 self.resolve_pattern_inner(p, pat_src, bindings);
1404 // Move up the non-overlapping bindings to the or-pattern.
1405 // Existing bindings just get "merged".
1406 let collected = bindings.pop().unwrap().1;
1407 bindings.last_mut().unwrap().1.extend(collected);
1409 // This or-pattern itself can itself be part of a product,
1410 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1411 // Both cases bind `a` again in a product pattern and must be rejected.
1412 let collected = bindings.pop().unwrap().1;
1413 bindings.last_mut().unwrap().1.extend(collected);
1415 // Prevent visiting `ps` as we've already done so above.
1428 pat_src: PatternSource,
1429 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1431 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1432 // (We must not add it if it's in the bindings map because that breaks the assumptions
1433 // later passes make about or-patterns.)
1434 let ident = ident.modern_and_legacy();
1436 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1437 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1438 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1439 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1440 // This is *required* for consistency which is checked later.
1441 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1443 if already_bound_and {
1444 // Overlap in a product pattern somewhere; report an error.
1445 use ResolutionError::*;
1446 let error = match pat_src {
1447 // `fn f(a: u8, a: u8)`:
1448 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1450 _ => IdentifierBoundMoreThanOnceInSamePattern,
1452 self.r.report_error(ident.span, error(&ident.as_str()));
1455 // Record as bound if it's valid:
1456 let ident_valid = ident.name != kw::Invalid;
1458 bindings.last_mut().unwrap().1.insert(ident);
1461 if already_bound_or {
1462 // `Variant1(a) | Variant2(a)`, ok
1463 // Reuse definition from the first `a`.
1464 self.innermost_rib_bindings(ValueNS)[&ident]
1466 let res = Res::Local(pat_id);
1468 // A completely fresh binding add to the set if it's valid.
1469 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1475 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1476 &mut self.ribs[ns].last_mut().unwrap().bindings
1479 fn try_resolve_as_non_binding(
1481 pat_src: PatternSource,
1488 self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?;
1489 let res = binding.res();
1491 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1492 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1493 // also be interpreted as a path to e.g. a constant, variant, etc.
1494 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1497 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) | Res::Def(DefKind::Const, _)
1498 if is_syntactic_ambiguity =>
1500 // Disambiguate in favor of a unit struct/variant or constant pattern.
1501 self.r.record_use(ident, ValueNS, binding, false);
1504 Res::Def(DefKind::Ctor(..), _)
1505 | Res::Def(DefKind::Const, _)
1506 | Res::Def(DefKind::Static, _) => {
1507 // This is unambiguously a fresh binding, either syntactically
1508 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1509 // to something unusable as a pattern (e.g., constructor function),
1510 // but we still conservatively report an error, see
1511 // issues/33118#issuecomment-233962221 for one reason why.
1512 self.r.report_error(
1514 ResolutionError::BindingShadowsSomethingUnacceptable(
1522 Res::Def(DefKind::Fn, _) | Res::Err => {
1523 // These entities are explicitly allowed to be shadowed by fresh bindings.
1529 "unexpected resolution for an \
1530 identifier in pattern: {:?}",
1537 // High-level and context dependent path resolution routine.
1538 // Resolves the path and records the resolution into definition map.
1539 // If resolution fails tries several techniques to find likely
1540 // resolution candidates, suggest imports or other help, and report
1541 // errors in user friendly way.
1542 fn smart_resolve_path(
1545 qself: Option<&QSelf>,
1547 source: PathSource<'_>,
1549 self.smart_resolve_path_fragment(
1552 &Segment::from_path(path),
1555 CrateLint::SimplePath(id),
1559 fn smart_resolve_path_fragment(
1562 qself: Option<&QSelf>,
1565 source: PathSource<'_>,
1566 crate_lint: CrateLint,
1568 let ns = source.namespace();
1569 let is_expected = &|res| source.is_expected(res);
1571 let report_errors = |this: &mut Self, res: Option<Res>| {
1572 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1573 let def_id = this.parent_scope.module.normal_ancestor_id;
1574 let node_id = this.r.definitions.as_local_node_id(def_id).unwrap();
1575 let better = res.is_some();
1576 this.r.use_injections.push(UseError { err, candidates, node_id, better });
1577 PartialRes::new(Res::Err)
1580 let partial_res = match self.resolve_qpath_anywhere(
1586 source.defer_to_typeck(),
1589 Some(partial_res) if partial_res.unresolved_segments() == 0 => {
1590 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1593 report_errors(self, Some(partial_res.base_res()))
1596 Some(partial_res) if source.defer_to_typeck() => {
1597 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1598 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1599 // it needs to be added to the trait map.
1601 let item_name = path.last().unwrap().ident;
1602 let traits = self.get_traits_containing_item(item_name, ns);
1603 self.r.trait_map.insert(id, traits);
1606 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1607 std_path.extend(path);
1608 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1609 let cl = CrateLint::No;
1611 if let PathResult::Module(_) | PathResult::NonModule(_) =
1612 self.resolve_path(&std_path, ns, false, span, cl)
1614 // check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1616 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1617 debug!("accessed item from `std` submodule as a bare type {:?}", std_path);
1618 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1619 hm.insert(item_span, span);
1620 // In some places (E0223) we only have access to the full path
1621 hm.insert(span, span);
1626 _ => report_errors(self, None),
1629 if let PathSource::TraitItem(..) = source {
1631 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1632 self.r.record_partial_res(id, partial_res);
1637 fn self_type_is_available(&mut self, span: Span) -> bool {
1638 let binding = self.resolve_ident_in_lexical_scope(
1639 Ident::with_dummy_span(kw::SelfUpper),
1644 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1647 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1648 let ident = Ident::new(kw::SelfLower, self_span);
1649 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1650 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1653 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1654 fn resolve_qpath_anywhere(
1657 qself: Option<&QSelf>,
1659 primary_ns: Namespace,
1661 defer_to_typeck: bool,
1662 crate_lint: CrateLint,
1663 ) -> Option<PartialRes> {
1664 let mut fin_res = None;
1665 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1666 if i == 0 || ns != primary_ns {
1667 match self.resolve_qpath(id, qself, path, ns, span, crate_lint) {
1668 // If defer_to_typeck, then resolution > no resolution,
1669 // otherwise full resolution > partial resolution > no resolution.
1671 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1673 return Some(partial_res);
1676 if fin_res.is_none() {
1677 fin_res = partial_res
1685 assert!(primary_ns != MacroNS);
1686 if qself.is_none() {
1687 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1688 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1689 if let Ok((_, res)) =
1690 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
1692 return Some(PartialRes::new(res));
1699 /// Handles paths that may refer to associated items.
1703 qself: Option<&QSelf>,
1707 crate_lint: CrateLint,
1708 ) -> Option<PartialRes> {
1710 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1711 id, qself, path, ns, span,
1714 if let Some(qself) = qself {
1715 if qself.position == 0 {
1716 // This is a case like `<T>::B`, where there is no
1717 // trait to resolve. In that case, we leave the `B`
1718 // segment to be resolved by type-check.
1719 return Some(PartialRes::with_unresolved_segments(
1720 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
1725 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1727 // Currently, `path` names the full item (`A::B::C`, in
1728 // our example). so we extract the prefix of that that is
1729 // the trait (the slice upto and including
1730 // `qself.position`). And then we recursively resolve that,
1731 // but with `qself` set to `None`.
1733 // However, setting `qself` to none (but not changing the
1734 // span) loses the information about where this path
1735 // *actually* appears, so for the purposes of the crate
1736 // lint we pass along information that this is the trait
1737 // name from a fully qualified path, and this also
1738 // contains the full span (the `CrateLint::QPathTrait`).
1739 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1740 let partial_res = self.smart_resolve_path_fragment(
1743 &path[..=qself.position],
1745 PathSource::TraitItem(ns),
1746 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
1749 // The remaining segments (the `C` in our example) will
1750 // have to be resolved by type-check, since that requires doing
1751 // trait resolution.
1752 return Some(PartialRes::with_unresolved_segments(
1753 partial_res.base_res(),
1754 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1758 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1759 PathResult::NonModule(path_res) => path_res,
1760 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1761 PartialRes::new(module.res().unwrap())
1763 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1764 // don't report an error right away, but try to fallback to a primitive type.
1765 // So, we are still able to successfully resolve something like
1767 // use std::u8; // bring module u8 in scope
1768 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1769 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1770 // // not to non-existent std::u8::max_value
1773 // Such behavior is required for backward compatibility.
1774 // The same fallback is used when `a` resolves to nothing.
1775 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
1776 if (ns == TypeNS || path.len() > 1)
1779 .primitive_type_table
1781 .contains_key(&path[0].ident.name) =>
1783 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1784 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1786 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1787 PartialRes::new(module.res().unwrap())
1789 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1790 self.r.report_error(span, ResolutionError::FailedToResolve { label, suggestion });
1791 PartialRes::new(Res::Err)
1793 PathResult::Module(..) | PathResult::Failed { .. } => return None,
1794 PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
1798 && result.base_res() != Res::Err
1799 && path[0].ident.name != kw::PathRoot
1800 && path[0].ident.name != kw::DollarCrate
1802 let unqualified_result = {
1803 match self.resolve_path(
1804 &[*path.last().unwrap()],
1810 PathResult::NonModule(path_res) => path_res.base_res(),
1811 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1812 module.res().unwrap()
1814 _ => return Some(result),
1817 if result.base_res() == unqualified_result {
1818 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1819 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
1826 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1827 if let Some(label) = label {
1828 if label.ident.as_str().as_bytes()[1] != b'_' {
1829 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
1831 self.with_label_rib(NormalRibKind, |this| {
1832 let ident = label.ident.modern_and_legacy();
1833 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1841 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &Block) {
1842 self.with_resolved_label(label, id, |this| this.visit_block(block));
1845 fn resolve_block(&mut self, block: &Block) {
1846 debug!("(resolving block) entering block");
1847 // Move down in the graph, if there's an anonymous module rooted here.
1848 let orig_module = self.parent_scope.module;
1849 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1851 let mut num_macro_definition_ribs = 0;
1852 if let Some(anonymous_module) = anonymous_module {
1853 debug!("(resolving block) found anonymous module, moving down");
1854 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1855 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1856 self.parent_scope.module = anonymous_module;
1858 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1861 // Descend into the block.
1862 for stmt in &block.stmts {
1863 if let StmtKind::Item(ref item) = stmt.kind {
1864 if let ItemKind::MacroDef(..) = item.kind {
1865 num_macro_definition_ribs += 1;
1866 let res = self.r.definitions.local_def_id(item.id);
1867 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
1868 self.label_ribs.push(Rib::new(MacroDefinition(res)));
1872 self.visit_stmt(stmt);
1876 self.parent_scope.module = orig_module;
1877 for _ in 0..num_macro_definition_ribs {
1878 self.ribs[ValueNS].pop();
1879 self.label_ribs.pop();
1881 self.ribs[ValueNS].pop();
1882 if anonymous_module.is_some() {
1883 self.ribs[TypeNS].pop();
1885 debug!("(resolving block) leaving block");
1888 fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
1889 // First, record candidate traits for this expression if it could
1890 // result in the invocation of a method call.
1892 self.record_candidate_traits_for_expr_if_necessary(expr);
1894 // Next, resolve the node.
1896 ExprKind::Path(ref qself, ref path) => {
1897 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
1898 visit::walk_expr(self, expr);
1901 ExprKind::Struct(ref path, ..) => {
1902 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
1903 visit::walk_expr(self, expr);
1906 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
1907 let node_id = self.search_label(label.ident, |rib, ident| {
1908 rib.bindings.get(&ident.modern_and_legacy()).cloned()
1912 // Search again for close matches...
1913 // Picks the first label that is "close enough", which is not necessarily
1914 // the closest match
1915 let close_match = self.search_label(label.ident, |rib, ident| {
1916 let names = rib.bindings.iter().filter_map(|(id, _)| {
1917 if id.span.ctxt() == label.ident.span.ctxt() {
1923 find_best_match_for_name(names, &ident.as_str(), None)
1925 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
1926 self.r.report_error(
1928 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
1932 // Since this res is a label, it is never read.
1933 self.r.label_res_map.insert(expr.id, node_id);
1934 self.diagnostic_metadata.unused_labels.remove(&node_id);
1938 // visit `break` argument if any
1939 visit::walk_expr(self, expr);
1942 ExprKind::Let(ref pat, ref scrutinee) => {
1943 self.visit_expr(scrutinee);
1944 self.resolve_pattern_top(pat, PatternSource::Let);
1947 ExprKind::If(ref cond, ref then, ref opt_else) => {
1948 self.with_rib(ValueNS, NormalRibKind, |this| {
1949 this.visit_expr(cond);
1950 this.visit_block(then);
1952 opt_else.as_ref().map(|expr| self.visit_expr(expr));
1955 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
1957 ExprKind::While(ref cond, ref block, label) => {
1958 self.with_resolved_label(label, expr.id, |this| {
1959 this.with_rib(ValueNS, NormalRibKind, |this| {
1960 this.visit_expr(cond);
1961 this.visit_block(block);
1966 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
1967 self.visit_expr(iter_expr);
1968 self.with_rib(ValueNS, NormalRibKind, |this| {
1969 this.resolve_pattern_top(pat, PatternSource::For);
1970 this.resolve_labeled_block(label, expr.id, block);
1974 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
1976 // Equivalent to `visit::walk_expr` + passing some context to children.
1977 ExprKind::Field(ref subexpression, _) => {
1978 self.resolve_expr(subexpression, Some(expr));
1980 ExprKind::MethodCall(ref segment, ref arguments) => {
1981 let mut arguments = arguments.iter();
1982 self.resolve_expr(arguments.next().unwrap(), Some(expr));
1983 for argument in arguments {
1984 self.resolve_expr(argument, None);
1986 self.visit_path_segment(expr.span, segment);
1989 ExprKind::Call(ref callee, ref arguments) => {
1990 self.resolve_expr(callee, Some(expr));
1991 for argument in arguments {
1992 self.resolve_expr(argument, None);
1995 ExprKind::Type(ref type_expr, _) => {
1996 self.diagnostic_metadata.current_type_ascription.push(type_expr.span);
1997 visit::walk_expr(self, expr);
1998 self.diagnostic_metadata.current_type_ascription.pop();
2000 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2001 // resolve the arguments within the proper scopes so that usages of them inside the
2002 // closure are detected as upvars rather than normal closure arg usages.
2003 ExprKind::Closure(_, IsAsync::Async { .. }, _, ref fn_decl, ref body, _span) => {
2004 self.with_rib(ValueNS, NormalRibKind, |this| {
2005 // Resolve arguments:
2006 this.resolve_params(&fn_decl.inputs);
2007 // No need to resolve return type --
2008 // the outer closure return type is `FunctionRetTy::Default`.
2010 // Now resolve the inner closure
2012 // No need to resolve arguments: the inner closure has none.
2013 // Resolve the return type:
2014 visit::walk_fn_ret_ty(this, &fn_decl.output);
2016 this.visit_expr(body);
2021 visit::walk_expr(self, expr);
2026 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
2028 ExprKind::Field(_, ident) => {
2029 // FIXME(#6890): Even though you can't treat a method like a
2030 // field, we need to add any trait methods we find that match
2031 // the field name so that we can do some nice error reporting
2032 // later on in typeck.
2033 let traits = self.get_traits_containing_item(ident, ValueNS);
2034 self.r.trait_map.insert(expr.id, traits);
2036 ExprKind::MethodCall(ref segment, ..) => {
2037 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2038 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2039 self.r.trait_map.insert(expr.id, traits);
2047 fn get_traits_containing_item(
2051 ) -> Vec<TraitCandidate> {
2052 debug!("(getting traits containing item) looking for '{}'", ident.name);
2054 let mut found_traits = Vec::new();
2055 // Look for the current trait.
2056 if let Some((module, _)) = self.current_trait_ref {
2059 .resolve_ident_in_module(
2060 ModuleOrUniformRoot::Module(module),
2069 let def_id = module.def_id().unwrap();
2070 found_traits.push(TraitCandidate { def_id: def_id, import_ids: smallvec![] });
2074 ident.span = ident.span.modern();
2075 let mut search_module = self.parent_scope.module;
2077 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2079 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2082 if let Some(prelude) = self.r.prelude {
2083 if !search_module.no_implicit_prelude {
2084 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2091 fn get_traits_in_module_containing_item(
2096 found_traits: &mut Vec<TraitCandidate>,
2098 assert!(ns == TypeNS || ns == ValueNS);
2099 let mut traits = module.traits.borrow_mut();
2100 if traits.is_none() {
2101 let mut collected_traits = Vec::new();
2102 module.for_each_child(self.r, |_, name, ns, binding| {
2106 match binding.res() {
2107 Res::Def(DefKind::Trait, _) | Res::Def(DefKind::TraitAlias, _) => {
2108 collected_traits.push((name, binding))
2113 *traits = Some(collected_traits.into_boxed_slice());
2116 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2117 // Traits have pseudo-modules that can be used to search for the given ident.
2118 if let Some(module) = binding.module() {
2119 let mut ident = ident;
2120 if ident.span.glob_adjust(module.expansion, binding.span).is_none() {
2125 .resolve_ident_in_module_unadjusted(
2126 ModuleOrUniformRoot::Module(module),
2135 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2136 let trait_def_id = module.def_id().unwrap();
2137 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2139 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2140 // For now, just treat all trait aliases as possible candidates, since we don't
2141 // know if the ident is somewhere in the transitive bounds.
2142 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2143 let trait_def_id = binding.res().def_id();
2144 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2146 bug!("candidate is not trait or trait alias?")
2151 fn find_transitive_imports(
2153 mut kind: &NameBindingKind<'_>,
2155 ) -> SmallVec<[NodeId; 1]> {
2156 let mut import_ids = smallvec![];
2157 while let NameBindingKind::Import { directive, binding, .. } = kind {
2158 self.r.maybe_unused_trait_imports.insert(directive.id);
2159 self.r.add_to_glob_map(&directive, trait_name);
2160 import_ids.push(directive.id);
2161 kind = &binding.kind;
2167 impl<'a> Resolver<'a> {
2168 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2169 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2170 visit::walk_crate(&mut late_resolution_visitor, krate);
2171 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2172 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");